語句

• continue — 跳過當前迭代中循環體的其餘部分的執行並跳轉到 while 語句的布爾表達式的計算。如果表達式的計算結果為真，則循環繼續。
• break — 立即終止當前迭代的執行並將控制轉移到循環後的第一條語句。因此，該語句結束當前循環的執行。我們將在下一篇文章中更詳細地討論它。

while (numberOfApplesInBowl > 0) {
    apple = bowl.grabNextApple();
    numberOfApplesInBow--; // "--" is the decrement operator, which reduces the number of apples by one
    if (apple.isBad()) { // This method returns true for rotten apples
        apple.throwInGarbage();
        continue; // Continue the loop. Jump to evaluation of numberOfApplesInBowl > 0
    }
    arrangeInPie(apple.peel().slice());
}

public static void main(String[] args) {
    int sum = 0;  // Total amount
    int i = 0;  // Initial number in the series
    int count = 20;  // Number of numbers
    while (i <= count) {
        i++;  // Get the next number — "i++" is equivalent to "i = i + 1"
        if (i * i <= count)  // If the square of the number is less than
            continue;  // the number of numbers, then we won't calculate the sum
                            // Jump to the next number in the loop
        sum += i * i * i;  // Otherwise, we calculate the sum of the cubes of numbers
    }  // "sum += i * i * i" is notation that is equivalent to "sum = sum + i * i * i"
    System.out.println(sum);  // Print the result
}

無限循環

while (true) {
    // Loop body 
}

public static void main(String[] args) {
    int base = 3; // The number that will be exponentiated
    int result = 1; // The result of exponentiation
    int exponent = 1; // The initial exponent
    while (true) {
        result = result * base;
        System.out.println(base + " raised to the power of " + exponent + " = " + result);
        exponent++;
        if (exponent > 10)
            break; // Exit the loop
    }
}

3 raised to the power of 1 = 3
3 raised to the power of 2 = 9
3 raised to the power of 3 = 27
3 raised to the power of 4 = 81
3 raised to the power of 5 = 243
3 raised to the power of 6 = 729
3 raised to the power of 7 = 2187
3 raised to the power of 8 = 6561
3 raised to the power of 9 = 19683
3 raised to the power of 10 = 59049
Process finished with exit code 0

嵌套循環

1. 如果碗裡有蘋果，那麼我們執行步驟1.1到1.4：

   1. 1.1. 拿一個蘋果
   2. 1.2. 去皮切成片
   3. 1.3. 把蘋果片放在平底鍋裡的餡餅皮里
   4. 1.4. 返回步驟 1。

1. 切片數 = 0

2. 只要切片數 < 12，則執行步驟 2.1 到 2.3

   1. 2.1. 從蘋果上切下另一片
   2. 2.2. 片數++
   3. 2.3. 返回步驟 2

1. 如果碗裡有蘋果，那麼我們執行步驟 1.1 到 1.6：

   1. 1.1. 拿一個蘋果
   2. 1.2. 去皮
   3. 1.3. 切片數 = 0
   4. 1.4. 只要切片數 < 12，然後執行步驟 1.4.1 到 1.4.3
   1. 1.4.1. 從蘋果上切下另一片
   2. 1.4.2. 片數++
   1.4.3. 返回步驟 1.4
   5. 1.5. 把蘋果片放在平底鍋裡的餡餅皮里
   6. 1.6. 返回步驟 1。

 public static void main(String[] args) {
    // Print the second factors in a row
    System.out.println("    2  3  4  5  6  7  8  9"); 
    int i = 2;  // Assign the first factor to the variable
    while (i < 10) {  // First loop: execute as long as the first factor is less than 10
        System.out.print(i + " | ");  // Print the first factor at the beginning of the line
        int j = 2;  // The starting value of the second factor
        while (j < 10) { // Second loop: execute as long as the second factor is less than 10
            int product = i * j;  // Calculate the product of the factors
            if (product < 10)  // If the product is a single digit, then we print two spaces after the product
                System.out.print(product + "  ");
            else  // Otherwise, print the product and one space after it
                System.out.print(product + " ");
            j++;  // Increment the second factor by one
        }  // Go to the beginning of the second loop, i.e. "while (j < 10)"
        System.out.println();  // Move to the next line on the console
        i++;  // Increment the first factor by one
    } // Go to the beginning of the first loop, i.e. "while (i < 10)"
}

    2  3  4  5  6  7  8  9

2 | 4  6  8  10 12 14 16 18 

3 | 6  9  12 15 18 21 24 27

4 | 8  12 16 20 24 28 32 36

5 | 10 15 20 25 30 35 40 45

6 | 12 18 24 30 36 42 48 54

7 | 14 21 28 35 42 49 56 63

8 | 16 24 32 40 48 56 64 72

9 | 18 27 36 45 54 63 72 81

Process finished with exit code 0